A bearing cage is a separator structure that keeps the individual rolling elements of a rolling element bearing evenly spaced around a race.
Usually, rolling element bearings are supplied with an amount of lubricant grease for lubricating purposes. Ideally, the grease gradually releases its oil content, thus ensuring an extended lubrication of the bearing. It is desirable to apply the grease as close as possible to the parts to be lubricated, e.g. the surface of the rolling elements. In particular, the amounts of grease which are collected on the cage bars are beneficial. These amounts are close to the rolling elements, thus enabling a direct supply of oil thereto.
However, centrifugal forces, which occur when a rolling element bearing is in use and limited adhesion have a negative influence on the grease retention capacity of the bearing cage. As a result, the grease on the cage bars may disappear, and collect in other areas where no supply of lubricant towards the center of the rolling elements or the raceways of the rings is possible.
U.S. Pat. No. 6,461,048 concerns a cage for a rolling element bearing with improved grease retention. The cage comprises at least one ring shaped body carrying regularly spaced cage bars, each pair of adjacent cage bars defining a cage pocket for accommodating a rolling element. At least one of the cage bars comprises elements situated radially outside and/or inside, the element(s) defining at least one space for accommodation of grease.